How to change color on the "Message box" (IMG inside)

[Burnt]

Curious how you go about changing the color of this box:


Or what to edit to change the text colors in this said box when you moderate and what not since both are set to a light color its hard to see the text?

*EDIT* Not the dark blue color inside but the light colored outside is what I want changed to a darker gray or changing the text in that box to a darker color.